This invention relates to rough electrical contact surfaces. For example, rough surfaces may be useful on contact pad surfaces in thin-film membranes used for testing integrated semiconductor devices. The contact pad surfaces make contact with device pads on the surface of semiconductor devices. See co-pending U.S. patent application Ser. No. 08/303,498. Because device pads can develop oxide layers, the membrane contact pads must penetrate oxide layers or other contaminants to make good electrical connections.
One method of penetration wears away the oxide layer by force often combined with rubbing motion. Another method of penetration uses contact pads having roughened surfaces that can pierce through the oxide layer. The roughened surface can be made, for example, by depositing already-formed, small, hard (e.g., of rhodium or titanium carbide) particles on the surface of a contact pad, and then electroplating the whole assembly with a thin layer of nickel.